资 源 简 介
The lower cost of high speed digital T1 and E1trunk lines has resulted in the increasing deploymentof this technology in place of traditionalanalog lines. In the past, T1/E1 trunks were usedprimarily in protected telephone company centraloffice transmission applications, but now theyare used outside the central office to bring highercapacity service directly to customers. Thebroader application of this technology makes itimportant for line card designers to include secondaryprotection circuitry in their designs.
